1. Field of the Invention
The present invention generally relates to an electronic apparatus, a method for controlling the power state thereof, and a storage medium for storing a program to realize the method. Aspects of the present invention may be applied to an electronic apparatus for controlling the power state thereof.
2. Description of the Related Art
A conventional printing apparatus may be in a normal energized state when communication with another apparatus is executed in order to print or acquire information and the like, and may change its state from the normal energized state to a power saving state when the communication with the other apparatus is finished.
FIG. 10 is a diagram illustrating an example of an internal configuration of such a printing apparatus.
In the example shown in FIG. 10, the power saving state is the state where a power source 1002 supplies power only to a local area network (LAN) controller 1001. To change from this power saving state to the normal energized state, first, the LAN controller 1001 identifies an electric signal (packet) input from a LAN 1003. Then, if the LAN controller 1001 determines based on the identified result that the power state is to be changed to the normal energized state, the LAN controller 1001 issues an order to the power source 1002 to energize a controller 1004. Further, the LAN controller 1001 issues an order to the power source 1002 to energize an apparatus body 1005, which includes a printer engine, for the actions of a printing request and the like.
Generally, to restore to the normal energized state from the power saving state, processing for initializing the controller 1004 and the apparatus body 1005 is typically performed, which takes a certain amount of time. Therefore, it may not be desirable to change the state unnecessarily. Further, if consumable parts, such as a hard disk and the like, are connected to the controller 1004, it may not be desirable to change the state unnecessarily.
A printing apparatus having such a power saving state function does not have a unit for explicitly determining whether communication with another apparatus is finished. Thus, as illustrated for example in FIG. 11, the printing apparatus may conventionally employ a mechanism that changes the power state from the normal energized state to the power saving state after a predetermined period of time has elapsed since the last communication with another apparatus.
However, there is a risk with such a mechanism that changes the power state from the normal energized state to the power saving state after a predetermined period of time has elapsed since the last communication with another apparatus, in that the energized state may be maintained for longer than is necessary. As illustrated in FIG. 12, a method to deal with this may be to simply shorten the waiting time (i.e., the above “predetermined period of time”) for changing to the power saving state. However, if this is employed, the power state can sometimes be changed from the normal energized state to the power saving state even though continuing packet communication is not finished, which is generally inefficient.
In another mechanism, as discussed in Japanese Patent Application Laid-Open No. 11-231977, a client changes the power state from the normal energized state to the power saving state in response to a control signal from a server.
However, this mechanism can be applied only between a pair of apparatuses. Therefore, when communicating with a plurality of apparatuses, the timing for changing the power state to the power saving state cannot be determined properly, so that the change to the power saving state cannot be performed at the appropriate time.
Furthermore, according to another mechanism the state of use of terminal apparatuses is collected, and the power state of the terminal apparatuses is changed from the normal energized state to the power saving state when a predetermined time, which is determined based on the collected state of use, has elapsed, as discussed in Japanese Patent Application Laid-Open No. 2003-256086. However, as described above, this mechanism may be inefficient, as the apparatus may be required to wait for a predetermined time in order to change to the power saving state.
Furthermore, according to yet another mechanism a peripheral apparatus transmits a response request at intervals of a predetermined time period to an information processing apparatus, to which there is a record of access, and if a response is not obtained for that response request, the power state is changed from the normal energized state to the power saving state, as discussed in Japanese Patent Application Laid-Open No. 2007-108862. However, in this mechanism, the information processing apparatus has to respond to a response request at intervals of a predetermined time period, during which the peripheral apparatus cannot be changed to the power saving state.